Expected Value Reroll Games Interview Questions
Expected value reroll games interview prep for keep-versus-reroll choices, thresholds, dice examples, and horizon mistakes.
Candidates preparing for common expected-value game variants.
Keep versus reroll
A reroll game compares the value of keeping the current outcome with the expected value of using a reroll.
Threshold strategy
If the reroll value is fixed, keep outcomes above that value and reroll outcomes below it.
Concrete example
With one fair die reroll available and final payoff equal to the shown roll, the value of rerolling is 3.5. Keep 4, 5, or 6 and reroll 1, 2, or 3.
More than one reroll
With multiple rerolls, compute the last decision first and work backward. The threshold can change by stage.
Optimal stopping link
Reroll games are small optimal stopping problems: stop with the current value or continue for an expected future value.
Common mistakes
Candidates often compare the current roll with the average original roll even when future reroll options change the continuation value.
Practice the pattern
Use the LeetQuidity curriculum and calibration to turn this topic into a focused practice plan.